Hard time hard numbers

Thursday, November 1, 2007

Exactly how much do problems with alcohol and other drugs contribute to crime? And how do we know? We thought it was a good opportunity to bust a myth – or at least take a closer look at the numbers in our own recent story.

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Last issue’s cover story, Rehabilitating our criminal justice system, started with, “It is said up to 80 percent of New Zealand’s crime is alcohol and drug-related, and about half of all offenders are using at least one drug at the time of their arrest.” So far, so clear. But depending on what you read, you might also find that:

  • “Around 60 per cent of all prisoners are affected by drug use at the time of their offending.”
  • “The Corrections Department says 89 percent of serious offenders were affected by drugs and/or alcohol in the period leading to their offences.”
  • “83.4 percent of inmates… have a substance abuse or dependence diagnosis.”

So: 60, 80 or 89 percent? And is it just drugs, or drugs and alcohol, affecting offenders?

As might be expected, different research produces different results. The figure cited in Matters of Substance came from a 2005 speech by Corrections’ Chief Executive Barry Matthews. The figure of 60 percent, widely quoted by ministers, comes from unpublished research cited in a 2006 Cabinet paper stating that, “Between 50 and 60 percent of offenders were affected by alcohol and/or other drugs at the time of their offending.”

References to “89 percent of serious offenders” originate from a 1998 report called A Seein’ “I” to the Future, on Corrections’ “criminogenic needs inventory” (“criminogenic needs” can be loosely translated as “factors contributing to offending that need to be addressed”). Prisoners’ alcohol and drug dependency data is from the 1999 National Study of Psychiatric Morbidity in New Zealand Prisons.

One reason that the figures differ is that one – 60 percent – refers to being affected at the time the offence was committed, while the larger number – 89 percent – is about alcohol or drug use in the period leading up to the offence.

The remaining question is, what evidence is there that alcohol and drug use contribute to offending?

Corrections’ view is supported by the evidence. Studies worldwide have found a high proportion of people convicted of crimes have alcohol or drug abuse or dependence. At the same time, people with substance use problems have much higher rates of criminal activity than the general population.

That drug use influences criminal activity has been known since the 1980s, when studies of “career addicts” found criminal activity was higher when they were more dependent, and lower in periods of low or no drug use.

As Canadian researchers found in 2002, the difference can be dramatic. Prisoners who had not used drugs or alcohol during a six-month period in freedom reported an average 1.7 crimes a week. Inmates who had used one or more substances while free, but were not dependent, had committed 3.3 crimes a week. Those dependent on drugs and/or alcohol had committed around seven crimes a week.

However, it is not as simple as saying, “drugs contribute to crime”.

Different drugs are linked to different kinds of crime, and while the media and public focus on illicit drugs, in fact, the strongest established drug-crime association is with alcohol.

The Canadian research is typical, finding that, with the exception of “gainful crimes” such as burglary, the highest proportion of crimes were connected to alcohol, or to alcohol and other drugs combined, with much lower proportions connected to illicit drug use. In general, alcohol consumption is connected to crimes of violence, while dependence on illicit drugs is connected to crimes for profit.

So while the numbers you come across may differ a little depending on the source, it doesn’t mean the relationship between drugs and crime is a myth. The correlation is demonstrably present and significant.

So, if we tackle addiction, do we reduce crime and re-offending? The Drug Foundation thinks so.

References